Method of forming a fibrous web using a variable transverse webber

ABSTRACT

A web or structure is formed by feeding separate supplies of fibrous material into contact with two separate lickerins that are parallel to each other and rotated toward each other. The fibers from the two lickerins pass through a mixing zone and are accumulated on a moving conveying screen that is moved parallel to the axes of the lickerins. Segmented baffle plates may be inserted into the mixing zone to control the lateral or cross-sectional composition of a web formed by the fibers accumulated on the screen. A segmented feed may be used to advantageously deliver different fiber materials at different rates to each lickerin. Radially layered composite web structures having circular cross-sections may be formed with the same apparatus by forming the conveying screen into a U-shape and selectively controlling the air flow through the screen.

This is a division of application Ser. No. 99,877, filed Sept. 22, 1987.

TECHNICAL FIELD

This invention relates to an improved method and apparatus for formingnonwoven structures consisting of a more or less uniform intermixture ofrandomly oriented fibers obtained from separate supplies ofindividualized fibers, such as textile and paper-making fibers.

BACKGROUND OF THE INVENTION

Nonwoven fiber structures frequently consist of a random yet homogeneousagglomeration of long and short fibers. Long fibers are fibers of bothnatural and synthetic origin that are suitable for textiles. They arelonger than 0.25 inches and generally range between 0.5 and 2.5 inchesin length. Short fibers are suitable for paper-making and are generallyless than about 0.25 inches long, such as wood pulp fibers or cottonlinters. It is known in the art that strong nonwoven structures can bemade by rapidly and reliably blending inexpensive short fibers withstrong long fibers.

Random distribution of the blended fibers results in an isotropic web orstructure that is uniformly strong in all directions. The fibers canalso be directionally disposed or aligned, resulting in an anisotropicfabric that is strong in the direction of alignment. Nonwoven fabricsare less costly than woven or knitted material, yet are more or lesscomparable in physical properties, appearance, and weight. Thus,inexpensive nonwoven fabrics are available for a wide variety ofproducts, including, hand towels, table napkins, sanitary napkins,hospital clothing, draperies, cosmetic pads, etc. These nonwoven webscan be particularly advantageous when formed as a layered or compositestructure having selective absorbent properties.

The desired utility and characteristics of the nonwoven end productdictate the types of fibers and the relative proportions of long andshort fibers in a web. The desired characteristics may include, forexample, tear resistance, abrasion resistance, stretchability, strength,absorption or non-absorption to different liquids, heat sealability, andresistance to delamination. Thus, a strong yet absorbent web mayadvantageously be formed from two or more long and short fibers, such asrayon and wood pulp combined in varying percentages.

There are many different methods and devices useful for making nonwovenwebs and other fibrous structures. Conventional carding or garnettingmethods produce nonwoven fiber webs, but these are generally and arelimited to textile length fibers.

The "Rando-Webber" process may be used to make nonwoven webs. In thisprocess, pre-opened textile fiber material is delivered to a lickerinthat opens the fibers further, and introduces them to a high-velocitylow-pressure air stream. The fibers are randomly deposited on acondensing screen to form an isotropic web. While a uniform web oftextile fibers can be obtained, this process is not suitable for usewith short fibers or blends of long and short fibers.

U.S. Pat. No. 3,512,218 of Langdon describes two lickerins and rotaryfeed condenser assemblies arranged in parallel one after the other.Isotropic nonwoven webs are formed with this apparatus by feedingfibrous material to the lickerins, where the fibers are individualizedand deposited on a condenser screen. A single airstream is divided intotwo parts and acts to doff the fibers from the lickerins and depositthem onto the screen, where the web is formed. This method cannot beused to homogeneously blend two streams of fibers.

In U.S. Pat. No. 3,535,187 of Woods there is described apparatus forproducing a layered web of randomly oriented fibers joined at theinterface of adjacent layers by a small zone of textile length fibersextending across the interface. Wood's device provides individualizedfibers which are deposited on a pair of cylindrical condenser screens bya pair of respective lickerins acting in cooperation with high-speed,turbulent air streams that move faster than the lickerin in order todoff the fibers. However, the air speed must also be controlled so thatthe fibers do not forcibly impact on the condensers. The condenserscreens are positioned closely adjacent to one another and the layers offibers on the condensers are compressed between the condensers to form acomposite nonwoven web with some blending at the interface betweenlayers. However, there is no substantial fiber mixing zone adjacent tothe condensers, and the intermixing of fibers is minimal.

One way of making a nonwoven web consisting of a mixture of randomlyoriented long and short fibers uses a milling device to individualizeshort fibers and a lickerin to individualize long fibers. The fibers aremixed in a mixing zone, and the mixture is deposited on a condenser toform a nonwoven web. Though randomly oriented, the mixed fibers arestratified rather than homogeneously blended. The long fiberspredominate on one side of the web and the short fibers predominate onthe other. In addition, undesirable clumps of fibers or "salt" occur inthis web product, because the mill does not completely individualize theshort wood pulp fibers.

Another method used to make webs of mixed and randomly oriented long andshort fibers introduces pre-opened long and short fibers to a singlelickerin for individualization. However, the optimum lickerin speeds forlong and short fibers are different. To prevent the degradation of longfibers, this device must operate at the slower speed that is optimum forlong fibers. As a result, the speed and throughput of the device iscompromised.

Methods and devices which produce a blend of long and short fiberswithout clumps or salt are disclosed in U.S. Pat. No. 3,772,739 ofLovgren. Lovgren provides for the separate and simultaneousindividualization of each type of fiber on separate lickerins, eachoperating at an optimum speed for the fiber it opens. For example, longfibers such as rayon are supplied to a lickerin operating in theneighborhood of 2400 rpm. Pulpboard is supplied to a lickerin operatingin the neighborhood of 6000 rpm, a speed that would damage long fibers.The fibers are doffed from their respective lickerins by separate airstreams and are entrained in the separate air streams. These streams aresubsequently mixed in a mixing zone in order to blend the fibers. Thehomogeneous blend is then deposited in a random fashion on a condenserdisposed in proximity to the mixing zone. While the Lovgren apparatus isuseful, it does not lend itself to the preparation of a wide variety ofwebs.

Another method of producing homogeneous blends of fibers is disclosed incommonly owned U.S. Pat. No. 3,740,797 of Farrington. Farringtondiscloses a method and machine wherein supplies of fibers are fed tooppositely rotating parallel lickerins, which are operated at respectiveoptimum speeds to produce individualized long and short fibers. Theindividualized fibers are doffed from the lickerins by centrifugal forceand by high velocity air streams directed against any fibers tending tocling to the lickerin structure. The individualized fibers from eachsupply are entrained in their respective air streams and are impelledtoward each other at high velocities along trajectories that intersectin a mixing zone, where at least a portion of the fibers from eachsupply may be blended. A condensing means or screen with a vacuumchamber below it communicates with the mixing zone so that the blendedfibers are deposited on the condenser screen within a condensing zone soas to produce an isotropic web of fibers. This screen is moved in adirection, i.e. the "machine direction," which is perpendicular to theaxis of the lickerins. In addition, a baffle can be interposed betweenthe air streams to control the degree of mixing and the respectivelocation of the long and short fibers in the composite web.

Farrington provides a method and apparatus for producing an air laidnonwoven web of homogeneously blended and randomly oriented short andlong fibers that is isotropically strong and is free of salt. WhileFarrington provides for a wide variety of nonwoven web products, thatprocess is still insufficient to produce many desirable nonwovenstructures or webs.

It is known to form cylindrical nonwoven web structures, such astampon-type sanitary products. This is accomplished by necking down acarded web of material into a sliver. The sliver is cut into sectionswhich are rolled into a cylindrical shape, and then compressed. Thisprocess has limitations in terms of the speed at which the product iscreated.

Thus it would be advantageous to provide a method and apparatus formaking thicker webs more rapidly than with the Farrington process, andwebs having a wider range of shapes and composite structures than can bemade on known machines by known methods.

SUMMARY OF THE INVENTION

The present invention is directed to the high-speed production of blendsof long and short fibers that result in a wide variety of compositenonwoven web structures of different widths, thicknesses, shapes andcompositions.

In an illustrative embodiment of the invention two independent fibersources driven by feed rolls are individualized by parallelcounter-rotating lickerins. The individualized fibers are doffed fromthe lickerins by air streams and centrifugal force, and are carried to amixing zone. The fibers may be randomly and uniformly mixed in the zoneor may be segregated by type, and then directed to a condensing zonewhere they are deposited onto a narrow condensing screen which islocated in the condensing zone. The mixing zone is below the parallellickerins and is defined generally by the space between the lickerinsand the condensing zone, which is below the mixing zone. The screen ismoved parallel to the axes of the lickerins, which is transverse to theconventional orientation. The motion of the screen with respect to thelickerins and the frame which houses them defines an input or rear endof the condensing zone, where the screen first enters the condensingzone and receives individualized fibers, and an exit or front end, wherethe formed web ceases to receive fibers and is expelled fromcommunication with the condensing zone. At any given moment duringoperation of the apparatus, the web is formed in the condensing zonebetween the input and exit ends, which also generally define theoperating length of the lickerins.

Duct plates are used to additionally define a path between the lickerinsand the condenser screen, and a vacuum chamber with a slot located belowthe screen is preferably used to form the air streams that doff thefibers from the lickerins and help deposit the fibers onto the screen.Since the screen travels parallel to and between the lickerins axes,there is a high-speed transverse formation of a web of nonwoven fibers.The transverse webber according to the invention provides a long webformation zone whose length is limited only by the practical length ofthe lickerins and whose width is limited only by the practical ductconfiguration between the lickerins and the screen.

Composite and layered structures can be made by varying the materialintroduced to the lickerins along the length of each lickerin. Webshaving different cross-sectional shapes can be generated by varying theconfiguration of the duct plates or the vacuum slot in the condensingzone, by introducing baffles into the mixing zone, or by programmablydriving the feed rolls, or combinations thereof. In one embodiment, thecondenser screen can be progressively curved, so that the web is given aform as it is condensed, rather than in a subsequent operation.

According to the invention, separate sources of short and long fibers,such as pulp and rayon, respectively, are individualized by separatelickerins and formed into a web. Each fiber source is guided by feedrolls and a nose bar into engagement with its lickerin, and eachlickerin is rotated at a high speed that is suitable for the fibers itis acting on. The two lickerins are parallel to each other and rotatetoward each other, i.e. in opposite directions. The nose bar andlickerin are arranged to provide a fiberizing station having the optimumopening relationship for the fibers. Each lickerin acts on its fibersupply and rapidly individualizes the fibers through violent contactbetween the fiber supply and the rapidly rotating teeth of the lickerin.

The counter-rotating lickerins create a centrifugal force that tends totangentially throw the individual fibers from each lickerin toward thefibers from the other lickerin. Gravity, an air stream naturallygenerated by the rotation of each lickerin, and the high speed airstream created by a suction force below the condenser screen tend toimpel the tangentially thrown fibers from the lickerin downward andtoward each other. These tangential and downward vector components carrythe individualized fibers to a centrally disposed mixing zone between,but below, the lickerins.

The stream of individual fibers entering the mixing zone from the twolickerins are dilute, allowing the two streams to intersect each other,such that the fibers cross each other without a substantial number ofcollisions. As a result, the fibers from the lickerin to the left of thecondenser screen tend to reach predominately the right side of thescreen and visa versa.

A different mixing pattern of the fibers can be accomplished byinserting a baffle into the mixing zone between the lickerins. Thisbaffle intersects part of each stream of fibers and deflects it back inthe opposite direction, such that the long and short fibers are spreadacross the lateral width of the web. This results in a proportionallyuniform mixing of the long and short fibers across the web. If thebaffle completely intersects the streams, the material from the lickerinon the left is reflected back to the left and vise versa, so that aproduct with a distribution essentially opposite that with no baffle iscreated. Therefore, the present invention produces products which mayhave different compositions than in the prior art, for example, websformed in laterally separated strips.

The deposition of fibers occurs as the condenser screen moves along thelength of the lickerins, e.g. 40 inches. Thus for the same screen speedand feed rate, the material deposited per inch of screen width isgreater than in the prior art wherein the lickerin axes areperpendicular to the screen movement direction and the condensing zoneis only the separation between the ducts extending from the lickerins,i.e. about 4 inches.

The width of the web is determined, according to the invention, by thedistance between the lickerins, if parallel ducts are used. However, theduct may diverge from the lickerins to the condensing zone. In such acase the width is determined by the angle of divergence and the distancefrom the lickerins to the screen, which are in turn limited by theability of the fiber/air stream to expand while maintaining a uniformflow profile without separation from the duct walls. When the condenserscreen is in the form of an endless moving belt, the length of the webis generally continuous, unless and until the supply of fiber isexhausted. The thickness and density of the web is determined primarilyby the fibers chosen, the proportion at which they are mixed, the feedroller speed, and the rate at which the condensing screen is moved.

Different composition pulp and textile fibers can be fed simultaneouslyto the respective lickerins in a side-by-side relationship. In one suchembodiment, pulp and textile fibers are fed into the device toward theinput end of the condensing zone to form a bottom layer of the web,while other materials are fed toward the exit end to form a top layer.In this way, different regions of the mixing zone can be definedcorresponding to the input fiber materials, and the resulting web can beformed as horizontal and vertical layers or web zones. Each web zone isintegrally associated with its adjacent web zone or zones byentanglement of the fibers across the interface; and each zone has adifferent but uniform composition of randomly oriented fibers.

When different fiber materials are introduced to each lickerin overdifferent portions of each lickerin length, a layering effect iscreated. The bottom layer is formed first on the condensing means. It iscreated from the fiber material fed to the most rearward portions of thelickerin, which are deposited at a location on the moving screenbeginning when it first enters the input or rear of the condensing zone.Successive layers may be formed by introducing different blends of fibermaterials to the lickerins downstream of the rear end, with the toplayer being formed by the blend of fiber materials fed to the mostforward end of the lickerins.

This horizontal layering effect is distinct from the vertical fiberzones within each such horizontal layer. The vertical zones result fromthe transverse and diagonal deposition pattern caused by the doffing offibers from the lickerins and their path of travel through the mixingzone and on to the condensing screen, a path which may be influenced bya vertical baffle and/or inclined shields in optional operating contactwith the mixing zone and condensing zone, respectively. Moreover, thehorizontal layers and vertical zones are independently formed, with theresulting composite web structure being defined by the number, types,and positions of the fiber materials fed to the lickerins, and thepositions of the vertical baffle and/or inclined shields.

When a common vertical baffle is used, the transverse or lateraldeposition patterns and resulting vertical zones within each layer ofthe web structure occur in groups, based on the groups of materials fedto each lickerin. However, a much wider variety of structures can beprovided by incorporating a segmented baffle assembly into theapparatus. The segmented baffle comprises at least two baffle segmentswhich can be selectively interposed within at least a part of the mixingzone and which can slide vertically with respect to each other. Thesegmented baffle defines sub-zones within the mixing zone, and thesesub-zones correspond to portions of the operating length of thelickerins. In this manner, both the horizontal and vertical depositionpatterns and the resulting horizontal layers and vertical zones can bevaried in concert over each segment of the forming web, resulting in anextremely wide variety of heretofore unknown composite structures.

The invention also provides a segmented feed, which advantageously andselectively delivers different fiber materials to a lickerin along aportion or segment of the lickerin length. The segmented feed is adaptedto adjust to the type of fiber and the desired end product, so that eachdifferent fiber material is fed to its portion of a lickerin underoptimum conditions of speed, position and rate of delivery to thelickerin, etc. In particular, the segmented feed is adapted toselectively receive fiber materials of different types and thicknessesfor fiberization at the fiberizing station, and the speed of the feedroller determines the concentration of those fibers in the web.

In yet another embodiment, the invention provides a method and apparatusfor forming radially layered cylindrical nonwoven web structures. Thecross-section of a web formed by a transverse webber need not berectangular and layered. For some applications, e.g. tampons, a circularcross-section is desirable. This can be achieved by forming the web witha transverse webber on a U-shaped condensing screen. The U-shaped screenis then further bent into a circular form by guides. The deposition offibers on the screen is made uniform by controlling the vacuum forcethrough the screen such that it is a minimum at the center and increasestowards both sides.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing advantages and numerous other features of the inventionwill be more readily understood and appreciated in light of thefollowing detailed description and accompanying drawings, wherein:

FIG. 1 is a schematic perspective view of a transverse webber accordingto the invention, showing the main components thereof;

FIG. 2 is a more detailed cross-sectional view of an apparatus accordingto the invention;

FIG. 3 is a side view of the apparatus of FIG. 2;

FIG. 4 is a fragmentary sectional view showing a portion of thecondenser seals;

FIGS. 5-7 illustrate cross sections of exemplary composite nonwoven webstructures;

FIGS. 8A and 8B are schematic top and end views of an apparatusaccording to the present invention with a fixed shield installed in thecondensing zone;

FIGS. 9A and 9B are cross-sectional and top views, respectively, of aproduct made according to the apparatus of FIG. 8;

FIGS. 10-15 illustrate cross-sectional views of products according tothe invention having horizontal and vertical web zones;

FIG. 16 shows a sectional view of a segmented feed roller according tothe invention;

FIGS. 17A and 17B show a composite product made with a segmented feedapparatus according to the invention;

FIG. 18 shows a perspective view, partially in section, of an apparatusfor forming radially layered and cylindrical nonwoven fibrousstructures;

FIG. 19 shows a side elevation of an apparatus for forming radiallylayered and cylindrical nonwoven fibrous structures; and

FIGS. 20A-20C schematically illustrate a method of forming cylindricalnonwoven structures according to the invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIGS. 1 and 2 show perspective schematic and cross-sectional views ofthe main components of an apparatus according to the invention. Theinvention is adapted to combine short and long fibers into a nonwovenweb having variable horizontal and vertical cross-sectionalcompositions. Principally the apparatus comprises two lickerins 10, 20operating in parallel. One lickerin 10 is adapted to individualize shortfibers and the other lickerin 20 individualizes long fibers. Theindividualization of the fibers, but not the formation of the web, isgenerally performed according to commonly owned U.S. Pat. No. 3,740,797to Farrington, the details of which are incorporated herein byreference.

Referring first to the short fibers, shown on the left in FIG. 1, woodpulp, in the form of a pulpboard 30, is directed between a plate 11(FIG. 2) and a wire wound feed roll 12. The plate 11 has a nose bar 13on its lower part, which provides an anvil for the pulpboard 30 duringindividualization of the short fibers. The fibers are individualized bythe rotating lickerin 10 disposed below the feed roll 12 and operativelyadjacent to the nose bar 13. The nose bar 13 assists in directing thepulpboard 30 along a path defined by the plate 11, the feed roll 12, thelickerin 10, the nose bar 13 itself, and an inclined face 15 adjacent tothe lickerin 10. These elements form a fiberizing station where thefibrous material, i.e., pulpboard 30, is converted into individualfibers. The inclined face 15 is spaced a short distance from the teeth16 of the lickerin 10 and the pulpboard 30 is individualized into fibersby the teeth 16 of lickerin 10 acting on pulpboard 30 as it is broughtin contact with the teeth 16 by the nose bar 13.

Typical short fibers include wood pulp fibers from various types ofwood, cotton linters, asbestos fibers, glass fibers, and the like. Woodpulp fibers are the most frequently used, due to their low cost andready availability. Pulp fibers are commercially available in the formof pulp boards of varying sizes and thicknesses.

For short fibers, the nose bar 13 may have a relatively flat sidewall 14(FIG. 2). The feed roll 12 is eccentrically mounted to permit adjustmentrelative to sidewall 14 and nose bar 13 as shown for example in FIG. 2by bracket 19. The bracket 19 and feed roll 12 are resiliently biased todirect the pulpboard 30 against the nose bar 13 by known means, and todrive the pulpboard into proper engagement with the teeth 16 of lickerin10. This design permits the use of pulpboards of varying thicknesses.

Feed roll 12 is supported on a shaft and is rotated by conventionalmotor means (not shown) at a speed determined by the rate at which thepulpboard 30 is to be fed to the lickerin 10. This rate determines theamount of pulp fibers deposited to form the web in a unit of time. Thepulpboard 30 is fed to the feed roll 12 in the direction shown by thearrow X in FIG. 1.

The lickerin 10 is likewise supported on a shaft and is rotated at apredetermined speed by a conventional motor (not shown). Lickerin 10 isadapted to rapidly and reliably fray and comb the pulpboard 30 byengagement with the teeth 16 until individual fibers are liberated fromthe pulpboard. Speeds in the neighborhood of 6000 rpm have been foundsuitable for this purpose. The teeth 16 are chosen to have an optimumprofile for the chosen short fiber material represented by pulpboard 30.

Long fibers are individualized in much the same manner as the shortfibers, as shown on the right side of FIGS. 1 and 2. Typical long fibersinclude synthetic fibers, such as cellulose acetate, vinylchloride-vinyl acetate and viscose staple rayon fibers, and naturalfibers, such as cotton, wool or silk. Long fibers, such as rayon, arecommercially available in bales, with varying fiber lengths.

A source of long fibers is provided, usually in the form of a cardedbatt 32, as when rayon is used as the fiber source. Batt 32 isintroduced to lickerin 20 via a second wire wound feed roll 22 acting incooperation with a plate 21 (FIG. 2) and a nose bar 23. However, thenose bar 23, adapted for use with long fiber sources, differs from thenose bar 13 used with pulp. Since rayon and other long fiber sourceslack the physical integrity of pulpboard, the batt 32 must be morepositively restrained and directed into engagement with the lickerin 20.As shown in FIG. 2, the nose bar 23 is curved to essentially conform tothe adjacent surface of the second feed roll 22. In this manner, thefibers in the rayon source are maintained in position with respect tothe second feed roll 22 until they are delivered to the teeth 26 oflickerin 20. The lickerin 20 is rotated at speeds such that the teeth 26can comb long fibers from the batt 32 without degrading or damaging thelong fibers. Speeds in the neighborhood of 3000 rpm have been foundsuitable for this purpose.

The teeth 26 of lickerin 20 are generally shorter than the teeth 16 oflickerin 10, and have a smaller pitch. Excellent results can be obtainedwhen the tooth pitch and height of teeth 26 each range between about1/8-1/4 inches. The angle of teeth 26 varies between -10 and +20degrees.

A support structure or frame and drive means are of course, provided forthe various elements of the invention, as shown generally in thefigures. Additionally, the nose bars, feed rolls, etc. can be adjustedwith respect to each other in order to achieve optimal results.

The long and short fibers may be individualized simultaneously orsequentially, and as shown in FIG. 1 there may be more than one type ofeach fiber (i.e., short fiber pulpboards A, B and long fiber batts C, D)distributed over portions of each lickerin. The lickerins 10, 20 arerotated toward each other, as shown by the arrows Y in FIGS. 1 and 2.The fiber sources, their distribution, and the speed and relativeproportions at which they are individualized, are chosen in order toproduce a nonwoven web having the desired structure and combination offibers.

The individualized long and short fibers are doffed from the lickerins,and are directed toward each other in a mixing zone 40. From the mixingzone the fibers pass to a condensing zone 44 containing a condenserscreen 42. This movement of the fibers is assisted by air streams. Asshown in FIG. 2, high velocity air streams, which doff the fibers anddirect them to condenser screen 42, can be established by a suctionforce created by a high vacuum chamber 49 located below the screen. Thisvacuum is formed by a fan driven by a motor (not shown) and drawnthrough duct 50 (FIG. 2). The vacuum draws air through ducts 35, 37,past the lickerins 10, 20 and the nose bars 13, 23, through the mixingzone 40 and the condensing screen 42, to the chamber 49. Since thefibers travel the same path as the air streams from the lickerins to themixing zone, the fibers are impelled to move more rapidly and reliablyfrom the lickerins 10, 20 to the condensing screen 42, where they formthe web 45. In order to assist in doffing fibers from the lickerins 10,20, the air streams are directed at the lickerin teeth 16, 26 at apredetermined angle and velocity, causing a uniform flow pattern at andaround the teeth. Advantageous manipulation of the air streams isfurther described in Farrington, U.S. Pat. No. 3,740,797.

The web 45 is formed in the condensing zone 44, which is a space belowand proximate to the mixing zone 40, just above the condensing screen42, and between duct plates 39. The length of the condensing zone 44corresponds to the length of the lickerins 10, 20. Thus, the condensingzone 44, according to the invention, is in the form of a long troughadapted to receive individualized fibers from above.

The duct walls 39 shown in FIG. 2 are parallel and define the width ofthe condensing zone 44. However, these walls may be replaced with walls39, that diverge (as shown in dotted line) at angles up to 15 or 20degrees, in order to form a web wider than the separation of thelickerins (FIG. 2).

The condensing screen 42 preferably comprises an endless conveyor thatis guided over conveyor rollers 52, 54, (FIG. 1), such that it may passabout the high vacuum chamber 49. One or both of the rollers 52, 54 aredriven so as to move screen 42 at a controlled rate.

When using entraining air streams, the vacuum chamber 49 willcommunicate with the condensing zone 44 through the mesh screen 42 via asuitable aperture 47 provided in suction plate 46 (FIG. 2). The aperturegenerally corresponds to the cross section of the space defined by theduct plates 39 and 59. The conveyor screen 42 is positioned to travelbelow and in communication with the condensing zone 44, and in adirection that is parallel to the axes of rotation of the parallellickerins 10, 20. As a result, the web 45 is formed as a continuoussliver expelled from the condensing zone 44 at right angles to thedirection of the fiber supply input and transversely with respect to therotating lickerins 10, 20. The web 45 is not condensed, as it is inknown devices, in a plane formed beneath the lickerins, having a widthcorresponding to the length of the lickerins, and moving perpendicularto the axis of rotation of the lickerins.

The thickness of the web according to the present invention is inverselyproportional to the speed of the screen 42. The faster the screen 42withdraws the forming web 45, the thinner the resulting web. However,the structure and orientation of the present condensing zone 44 withrespect to the mixing zone 40 permits much thicker, albeit narrower,webs to be formed far more rapidly than by other prior techniques.

The screen 42 may communicate with other conveyors, thereby deliveringthe web 45 for further processing as desired. Such processing mayinclude bonding, as described for example in Lovgren, U.S. Pat. No.3,772,739; shape-forming procedures; and final finishing of the webproduct.

In order to seal off the lower ends of ducts 39 and to maximize theefficiency of the suction fan, duct plates 39 are extended downwardtoward the screen 42 and terminate just above the screen 42. The ductplates 39 may additionally be provided with floating seals 53, which arebiased into contact with the screen 42 by a spring located behind thefloating seals in a recess in plates 39 (FIG. 4.. Lickerin covers 55(FIGS. 2 and 8B) may also extend about the outer periphery of thelickerins and engage plates 39 to provide an additional seal for thevacuum which forms the air streams.

At the places where the screen 42 enters and leaves the condensing zone44, rolling seals 57, 56, respectively, are provided on duct plates 59(FIG. 3). The sealing rolls 56, 57 are disposed between the paralleledges of duct plates 39 and are free to rotate on the screen and web toaccommodate movement of the screen and web. When the web 45 exits thecondensing zone 44 supported by the screen 42, it passes beneath sealingroll 56. Besides maintaining the vacuum, the duct plates 39 serve toguide the fibers to the condensing zone 44 and together with the plates59, the floating seals 53, and sealing rolls 56, 57, they improve theefficiency of the suction air flow.

The device of FIGS. 1 and 2 is provided with a retractable baffle 60disposed within a plane passing perpendicularly between the lickerins10, 20 and intersecting the mixing zone 40. Although the baffle can beplaced so that its downward leading edge falls at any predeterminedpoint at or above the moving condenser screen 42, three distinctqualitative positions can be defined. When the baffle 60 is in the up orfully retracted position, its leading edge is removed from anyfunctional contact with the fiber streams leaving the lickerins. Whenthe baffle 60 is fully down, its downward leading edge is at or abovethe screen 42 at a predetermined position within the mixing zone 40where it completely intercepts the fiber streams. Finally, the baffle 60can be positioned so that its downward leading edge corresponds to apredetermined blend point within the mixing zone 40 where it partiallyblocks the fiber streams. A wide variety of composite structures can begenerated by varying the position of the baffle 60 and by feeding one ormore materials via each of the feed rolls 12, 22. FIGS. 5-7 illustrateexemplary composite nonwoven web structures as described according tothe following examples. It will be understood by skilled practitionersthat these examples represent only a few of the many structures that canbe made. Moreover, it will be evident from the examples that, because ofthe transverse discharge of the web 45, a uniformly blended web isformed which is unobtainable in the same manner in known devices, suchas the Farrington method and apparatus. On the contrary, the transversewebber tends to deposit the fibers into a web according to uniquezone-forming patterns. These patterns can be manipulated to produce newand useful composite structures.

EXAMPLE 1

The same fiberizing stations (i.e. lickerin, nose bar and feed roller)are set up at each side of the screen. Then identical short fiberpulpboards 30 or long fiber batts 32 are supplied to both of thelickerins 10, 20, via the feed rolls 12, 22. The resulting web 45 is ahomogeneous nonwoven web consisting of one kind of fiber. The result isthe same for any position of the baffle 60.

EXAMPLE 2

Two different fiber materials 30, 32 in the form of short and longfibers A, C, respectively, are delivered to the feed rolls 12, 22respectively, with each different fiber source being coextensive withone of the lickerins 10, 20. When the baffle 60 is in the up position, acomposite web is formed having three lateral zones, each running in themachine direction. A schematic cross-sectional view of this product isshown in FIG. 5.

The zone-like composite structure is a consequence of the trajectoriesof the fibers doffed from the lickerins, passed through the mixing zone40 and then formed into a transverse web within the condensing zone 44.In a conventional webber, any such nascent zones tend to be cancelled orunified by continuous withdrawal of the forming web in the standardlongitudinal machine direction, i.e. the direction in which such zoneswould form. However, by withdrawing the forming web in the transversedirection, the zones form as a result of the fiber deposition patterncaused by the fiber trajectories.

When the baffle 60 is up, it does not alter the dilute fiber/air streamtrajectories as they pass through the mixing zone 40 to the condensingzone 44. The fibers within the air streams retain a component of motiontending to throw them away from their respective lickerin and toward theweb on the side of the opposing lickerin. As a result, the fibers tendto pass each other within the mixing zone 40 because the streams are sodilute that there is little tendency for fiber collisions. Thus, thefibers are predominantly deposited toward opposite sides of thecondensing zone 44. As shown in FIG. 5, short fibers A originating froma left-hand lickerin tend to form a narrow right-hand fiber zone Acontaining predominantly fibers A. The long fibers C originating fromthe right-hand lickerin tend to form a narrow left-hand zone Ccontaining predominantly fibers C. Between the fiber zones A and C is awider transition zone containing a blend of fibers A+C. At theboundaries of the zones the fibers are entangled so that the web isformed in one piece.

EXAMPLE 3

The fiber sources of Example 2 are used, but the baffle 60 is positionedat a blend point within the mixing zone 40 in order to influence thetrajectories of the individualized fibers prior to final deposition as aweb on the screen 42. The individualized fibers passing through themixing zone 40 and on to the condensing zone 44 from each lickerin fallwithin a range or angle of trajectories, in the manner of a sprayexiting a nozzle. The baffle 60, when positioned at the predeterminedblend point, intersects at least part of the trajectory angle, causingsome of the fibers and any entraining air flow within that part of theangle to bounce off the baffle 60 back toward its own originating sideof the condensing zone 44.

If the baffle blend point is chosen so that approximately equal volumesof fiber from each lickerin are redirected by the baffle 60, as arepermitted to pass under the baffle 60 without interruption, a uniformlyblended web of short and long fibers A+C is obtained. The blend pointcan, of course, be chosen to provide a wide variety of fiber depositionpatterns and resulting nonwoven web structures.

EXAMPLE 4

In yet another embodiment, the baffle 60 is placed in a down position,approximately 2 inches above the screen 42. The two different fibersources A, C of Example 2 are used such that each fiber is supplied overan operative length of one of the parallel lickerins 10, 20. In thiscase, substantially all of the fiber trajectories are interrupted by thebaffle, tending to throw the fibers back toward their originating sideof the condensing zone 44. The result is a web similar to the web inExample 2, but with the fiber zones A and C in reverse order, and anarrower transition zone A+C as shown in FIG. 6.

It should be appreciated that regardless of the position of the baffle,there will be some distribution of both long and short fibers across theweb due to the turbulent air flow. Thus the zone representations inFIGS. 5 and 6 merely show the predominant fibers in each. The proportionof fibers in each zone may also be regulated by the rate at which thefiber sources 30, 32 are fed to the lickerins. A fiber fed at a fasterrate will produce a greater concentration of that product in the web,although it will be distributed across the web in a manner determined bythe baffle position.

Each lickerin 10, 20 need not be supplied entirely with one fibersource, provided that all of the fibers supplied to each lickerinconform to the fiber type (short or long) for which the lickerin isadapted. Thus, for example, four fiber sources A-D can be equallydistributed among the two lickerins, each such source covering half ofits respective lickerin. FIG. 1 illustrates this embodiment. Thepulpboard 30 has a portion with short fibers A and another portion withshort fibers B, both of which are fed to lickerin 10. Textile fiber batt32 also has two portions for producing long fibers C, D which are fed tolickerin 20. The fiber combination A, C toward the input end of theapparatus produces a lower layer of the web, while the fiber combinationB, D toward the exit end of the apparatus produces an upper layer. Thus,the resulting product has both lateral zones, and vertically-arrangedzones or layers of fiber compositions.

EXAMPLE 5

The multiple fiber supplies A-D of FIG. 1 are fed to the apparatus withthe baffle in a blend point position to promote uniform mixing anddeposition of fibers. The two rearward fiber sources A and C in themachine direction apply their fibers on a portion of screen 42 first. Asthis portion of the screen moves toward the exit it passes below thetransition between sources AC and BD, and a transition layer having amixture of all four fibers is laid down on top of the lower layer, whichis a uniform blend of fibers A and C. As the screen portion moves underthe region of the lickerins which is fed fibers B, D, these aredeposited as an upper uniformly blended layer B and D. A cross sectionof this product is shown in FIG. 7.

EXAMPLE 6

An alternative product as shown in FIG. 9 may be made by installingfixed shields 62 (FIG. 8A and 8B) in the condensing zone 44 toward themiddle of the machine and feeding three separate portions to thelickerin, i.e. A and C, B and D and A and C. The fixed shields 62 aregenerally disposed at a horizontal position above the forming web in themiddle where fiber portions B and D are laid down. Thus a first widelayer 65 is deposited which is a mixture of fibers A and C. (FIG. 9A).Then a middle layer 66 can be added. This layer is narrower andcomprises fibers B and D because shields 62 make the condensing zonenarrower (FIG. 8B). Finally, a third or top layer 67 is added. Layer 67may also be a blend of fibers A and C so that the middle layer 66 offibers B, D is completely surrounded by fibers A and C.

A product in which a middle layer is surrounded by other layers can bevery advantageous as an absorber, e.g. a diaper or sanitary napkin. Withsuch a product the inner fiber blends, e.g. B and D, in layer 66 of FIG.9A, are selected to be high absorbency fibers. For example this layermay be made predominately of pulp or super-absorbing fibers. The outerfibers, e.g. A and C are selected for their wicking properties, i.e. theability to move liquid. For example, Rayon fibers have good wickingproperties. With such a product the moisture is directed away from theuser's skin and clothing by the wicking fibers and is retained in thecenter of the product by the high absorbency fibers.

If the feeding of the pulp or high absorbency fibers is intermittent,separate patches of this material will be buried along the web (FIG.9B). In later processing the web can be separated between these patchesto form individual products. For example, these products may be surgicalpads with absorbent, inexpensive, but unattractive pulp layers,concealed by a polyester cover layer.

EXAMPLE 7

As a further modification, powder dispensers in the form of trays 69 maybe located above plates 11, 21 as shown in FIG. 2. These dispensers maybe used to introduce super absorbent powders or other materials into theweb as it forms by introducing the materials into the air streams thatdoff fibers from the lickerins. In particular, the doffing air streamsare created by a suction force in chamber 49. This draws air from theatmosphere, through channels 18, 28, over the lickerins, through mixingzone 40, through condensing zone 44 to chamber 49. By placing trays 69at the entrance to channels 18, 28, the particulate material in thetrays is drawn into these channels and mixes with the fibers formed atthe lickerins.

If these trays are positioned near the center of the axes of thelickerins, the particulate material will end up in the center of theweb. In particular, a first layer, e.g. one predominated by fibers withgood wicking properties can be laid down by feeding fibrous material ofthis type in the positions A and C in FIG. 1. Then, as the forming webmoves under the part of the lickerins where the trays 69 are located,the fibers will be mixed with, e.g. super absorbent powder. Also, thefibers in this zone may be predominantly absorbent, e.g. pulp. Thus ahighly absorbent middle layer is formed. This layer may be made narrowerthan the bottom layer if shields 62 (FIG. 8B) are included in the regionbelow the tray 69. Finally a top layer of good wicking fibers is addedto the web just before it exits the condensing zone. In this way, theinvention provides a super absorbent core surrounded by fibers thatprovide good wicking properties.

EXAMPLE 8

FIGS. 10-12 show a horizontal layering effect achieved by the inventionwhen different fiber materials are fed to the lickerins along segmentedportions of the lickerin length, in cooperation with a common verticalbaffle 60 (FIG. 2). The blend of fibers doffed and condensed at the rearform the bottom layer. Successive layers corresponding to each differentlickerin segment are deposited over the bottom layer as the forming webmoves downstream, from the rear to the front.

When a common baffle 60 is used, it controls the blending of fibers invertical zones without regard to the number of parallel supplies offiber material. In the example of FIGS. 10-12, which is representativeof this phenomenon, four different fiber materials are supplied, eachbeing coextensive with half the operating length of a lickerin. Thus,fibers A and B are fed to one lickerin and fibers C and D are fed to theother, with A and C being fed at the rear and B and D being fed at thefront, as in Example 5. Fibers A and C will be deposited first, to forma bottom layer, followed by overlapping deposition of fibers B and D toform a top layer. As shown by FIGS. 10 , fibers A and C will always begrouped together horizontally and fibers A and B will always be groupedtogether vertically. Similarly, fibers B and D will always be togetherhorizontally and C and D will always be together vertically. Theposition of the common vertical baffle 60 does not change thisrelationship, although it does change the blend composition andhorizontal positions of the fibers in the product.

FIG. 10 shows a product according to an embodiment where the baffle 60is fully down, resulting in a composite material having three horizontallayers (B, BD, and D on top; A, AC, and C on the bottom), and a thinhorizontal transition layer between the other two horizontal layers.

FIG. 11, which is similar to FIG. 7, shows a product according to anembodiment where the baffle 60 is positioned at a blend point within themixing zone. The result is a three layer composition: a bottom layer ofA and C uniformly mixed according to predetermined proportions, a toplayer of B and D uniformly mixed according to predetermined proportions,and a thin transition layer between them.

FIG. 12 shows a product according to an embodiment where the baffle 60is fully up, resulting in a composite product formed generally as amirror image of the product shown in FIG. 10, except that the centralblended vertical zones of fibers BD and AC are wider.

Instead of one piece, baffle 60 may be formed as segmented baffle 60a,60b with two or more sections (FIG. 1). Each segment of the bafflecorresponds to a different portion of the operating length of thelickerins. In a preferred embodiment, each segmented baffle correspondsto a different pair of input fiber materials, optionally delivered bysegmented feed rollers, as shown in FIG. 16.

EXAMPLE 9

FIGS. 13-15 represent products obtained with a segmented baffle, wherefiber materials A and C are fed to a rear segment of their respectivelickerins within a lickerin length corresponding to a first bafflesegment 60a vertically and optionally disposed within at least part ofthe mixing zone (FIG. 1). Fiber materials B and D are fed to a frontsegment of their respective lickerins within a lickerin lengthcorresponding to a second baffle segment 60b. The baffle segments can bepositioned independently in the up, down or blend positions, to achievea very wide variety of composite shapes.

FIG. 13 shows a product obtained when the first baffle segment 60a(corresponding to fiber materials A and C) is down and second bafflesegment 60b (corresponding to fiber materials B and D) is in a blendposition. This arrangement results in a bottom layer of materials A, ACand C deposited due to interference with the fiber streams from thebaffle, a blended top layer of fiber materials B and D, and a thintransitional layer between the top and bottom layers. Essentially, thesegmented baffle results in this instance in a composite structurecombining the bottom layer of FIG. 10 with the top layer of FIG. 11.

In FIG. 14, the product is created by the device with the positions ofthe baffle segments 60a and 60b altered with respect to their positionsfor the creation of the product of FIG. 13. When the first bafflesegment 60a is down and the second baffle segment 60b is fully up, amulti-layer and multi-zone structure is formed, combining the top layerof FIG. 12 with the bottom layer of FIG. 10. These positions arereversed to form the product in FIG. 15, with first baffle segment 60afully up, and second baffle segment 60b fully down.

It will be appreciated that an extremely wide variety of new compositestructures can be generated by the manipulation of baffle segmentscorresponding to different fiber materials input over different portionsof a lickerin length, the different fiber materials being chosen andpositioned to produce a horizontally layered nonwoven web havingvertical zones.

The invention also provides for segmented feed rollers, as shown in FIG.16. The segmented feed provides a means of advantageously deliveringdifferent fiber materials to different segments or longitudinal portionsof each lickerin at varying rates. In this manner, different fibermaterials of the same type (e.g. long or short), can be readily fed to asingle lickerin, and corresponding pairs of materials can be fed toparallel portions or segments of the parallel lickerins in a transversewebber, in order to provide composite nonwoven web structures havingdifferent blend ratios for any pair of materials being fed to thelickerins.

The segmented feed assembly comprises at least two feed roll segments101a, 101b (FIG. 16) mounted on a common stationary shaft 102. The feedroll segments are each selectively adapted to receive particular fibermaterials for delivery to a common lickerin at different predeterminedrates, over a longitudinal portion or segment of the operating length ofthe lickerin. In this way, the blend ratio can be altered and optimized,depending on the desired end products, and more than one blend ratio ispossible.

The blend ratio of a composite web is a function of the weight per unitarea of the incoming individual fibers as determined by the rotationalspeed of the feed roll. With a conventional feed, there are only twofeed rolls, one for each lickerin, each operating at a compromise speedchosen according to the fibers to be individualized and the desired endproduct. Thus, the use of a conventional feed in a transverse webber canresult in only one blend ratio of left-hand fibers to right-hand fibers,no matter how many different fiber compositions are introduced along theoperating length of each lickerin. The segmented feed permits aplurality of blend ratios, each confined to its own lickerin segment.

Motors (not shown) are used to drive gear trains that mesh with gear104a, 104b. Gear 104a meshes with a gear 106a that is rigidly fastenedto an outer end of feed roll segment 101a. As a result, feed rollsegment 101a will rotate and feed material to its corresponding lickerinportion at a rate determined by the rotation of gear 104a and the gearratio of gears 104a and 106a. Likewise, gear 104b meshes with a gear106b that is rigidly attached to feed roll segment 101b by a cylindricaldrive shaft 108. Shaft 108 is also mounted on the common stationaryshaft 102. As a result, feed roll segment 101b is rotated and feedsmaterial to its lickerin portion at a rate determined by gear 104b(which rate is independent of the speed of gear 104a) and the gear ratioof gears 104b and 106b.

By means of bearings 110, the cylindrical shaft 108 and the feed rollsegments 101a and 101b are rotatable with respect to stationary shaft102.

Should more than two feed roll segments be desired for a singlelickerin, e.g. four segments, the other feed roll segments, e.g. 103b,may be driven in the same way as that shown in FIG. 16 for segments101a, 101b, except reversed so that the drive mechanism, i.e. the gears,are located toward the outer edges of the feed roll assembles, asopposed to having part in the middle, which would cause a break in thefiber flow streams. Feed roll segments could be driven by othermechanical means than the gears shown, e.g. by chains or belts.

EXAMPLE 10

FIG. 17 illustrates a product made using the segmented feed, comparedwith one made using a conventional feed. Fiber materials A and B areprocessed on one lickerin and C and D are processed on the otherlickerin, with A and C at the rear and B and D at the front. All of thefiber materials are of equal length along the lickerins. If a commonbaffle 60 is at a blend position, a composite material results,comprising a blend of A and C as a lower layer and a blend of B and D asan upper layer, with a fixed blend weight ratio of A/C=B/D (FIG. 17A).

But, if the feed rolls are segmented as shown in FIG. 16, using the samefiber materials and distribution A-D, such that each lickerin isprovided with two different fiber materials at two different speeds,then the blend ratios become variable. One such embodiment, where theratios A/C and B/D are independent, is shown in FIG. 17B. Here the feedrollers for fibers A, C are rotated at a higher speed than the segmentsfor fibers B, D. Consequentially, the lower region of the web is thickerthan the upper layer.

As an alternative, the A fiber segment may be rotated at a higher speedthan the B segment, so that in the lower layer there is more A fiberthan there is B fiber in the upper layer. Thus, in FIG. 17A wherein thesegments of each feed roll have the same respective speed, the fiberratios are the same for each layer, i.e., A/C=B/D. However, in FIG. 17Ba product is shown where the B segment is rotated slower than the Asegment so that A/C>B/D. Other variations are obvious from the abilityto simultaneously feed materials to different lickerins or differentparts of the same lickerins at different independent rates.

Still another embodiment of the invention is shown in FIGS. 18-20, whichillustrate an apparatus for forming radially layered cylindricalnonwoven structures on a transverse webber. In such an apparatus, thecondensing means, as shown in FIGS. 18 and 19, comprises a flat,continuous and flexible screen belt 101 moving in a machine directionthat is transverse to the plane within which the lickerins are rotating,i.e., parallel to the lickerin axes. The direction of travel of the belt101 also defines a rear end R, where the belt 101 first enters thecondensing zone C and first receives fibers. The front end F is thepoint where the belt 101 exits the condensing zone C and ceases toreceive fibers.

The belt 101 is at least partially confined within a U-shaped trough 102disposed beneath the mixing zone 103 of a fiber webber, from which thebelt 101 receives fibers doffed from the lickerins and mixed in themixing zone, as entrained by fiber-carrying air streams 104. The airstreams 104 are created or supplemented by a vacuum chamber or suctionbox 105 disposed below the trough 102 and the belt 101, andcommunicating with the belt 101, preferably through a perforated support106. The belt 101 is driven through the trough 102 and beneath themixing zone 103 by rollers 107 and conventional motors (not shown), withthe direction of motion indicated by the arrows Z in FIGS. 18 and 19.The mixing Zone 103, belt 101, trough 102, perforated support 106 andsuction box 105 provide a downward vertical path for fibers and theirentraining air streams 104. The fibers exit the mixing zone 103 underthe influence of gravity and the streams 104 and are deposited on thebelt 101, causing the forming web to conform to the U-shape imposed onbelt 101 by trough 102. The air streams 104 continue through thecondensing fibers, belt 101, and perforated support 106, andoperationally terminate within suction box 105. In this manner, many newcomposite web structures having non-rectangular cross-sections may beproduced.

In a preferred embodiment, the trough 102 and the corresponding U-shapedportion of belt 101 are coextensive with the mixing zone 103, which inturn is coextensive with the condensing zone C and the operating lengthof the lickerins of the transverse webber, which in turn corresponds tothe front and rear ends, F and R.

As shown in FIGS. 18 and 19, parallel duct plates 108 descend from themixing zone 103 to create seals 109 with the trough 102 (FIG. 18), inorder to assist the suction created by suction box 105 and to confinethe air streams and fibers within an optimum condensing zone. In thepreferred embodiment, the duct plates 108 are provided with recesses110, which are adapted to receive the edges of the belt 101 as it passesthrough trough 102 and is deformed into the desired U-shape. Thus, thecondensing zone C is advantageously contained and preferably sealedwithin a volume defined by the mixing zone 103 above, the U-shapedportion of belt 101 below, the duct plates 108 at the sides, and thefront and rear ends, F and R, Which may contain rolling seals.

The belt 101 is not U-shaped over its entire continuous length. Instead,the belt 101 arrives proximate to the rear end R as a flat continuousbelt. Means, e.g., in the form of sealing roll 111, are provided topartially deform the belt, so that it may be received by the trough 102and further deformed into the desired U-shape over the desired length.The forming roller 111 is biased into contact with the belt 101 and alsoserves to seal the rear end R of the condensing zone C, with respect tothe fibers and air streams 104. A similar roller, not shown, may belocated at the front end F, but is not necessary because of the sealingeffect of the forming web tube and guide plates 112.

In the exemplary embodiment of FIGS. 18 and 19, the forming roller 111partially deforms belt 101, so that its edges leave the flat planewithin which the belt is traveling, whereupon the edges may be entrainedwithin recesses 110 and drawn against support 106 by the suction force.

As the U-shaped portion of belt 101 exits the trough 102 at the frontend F, the suction force is eliminated and it is delivered to formingshoes or guide plates 112, which may be in the form of aconvergent-divergent forming tube as shown in FIGS. 19 and 20C. In thismanner, the U-shaped belt portion 101 and the formed web it now carriesare further deformed into a cylindrical shape, so that a composite webstructure having radial layers and a circular cross section is formed.The now cylindrical product is moved further along, and the guidestructure opens up and allows the product to exit the guide 112. The webproduct is then separated from the belt 101, and belt 101 is permittedto collapse back to its flat configuration. It then travels about rolls107, and eventually back to the condenser zone.

In operation, a homogeneous cylinder can be obtained by feeding only onematerial to the lickerins, or by feeding two materials, one to eachlickerin, to obtain a homogeneous blend. Radially layered structures canbe obtained by feeding materials to the lickerins toward the rear end Rwhich are different than the materials fed toward the front end F.

The operation of the apparatus and a method of making cylindricalcomposite structures, are illustrated by FIGS. 20 A-C, which are drawnalong the section lines AA', BB', and CC' of FIG. 19, respectively.

A uniform layer of fibers 122 (FIG. 20A) can be achieved, despitegravity effects, by controlling the airflow distribution through thescreen belt 101, for example by selectively perforating the support 106and/or subdividing the suction box to provide independent suction todifferent cross-sectional areas of the belt 101 as it passes through thecondensing zone C.

Since gravity and the trajectories of the fiber from the lickerins wouldtend to cause most of the fibers to accumulate at the bottom of trough102, i.e. at the center of the web, action must be taken to make theheight of the formed web uniform. To accomplish this, the airflowdifferential provided by suction box 105 must oppose the gravity andinertial fiber forces that tend to deposit all of the material at thebottom of the "U", while leaving the vertical sides uncovered. This mayrequire that there be no suction force at the bottom of the U-shape andmaximum force at the vertical edges.

The suction at the vertical sides must be maintained throughout thecondensing zone so that the layer 122 toward the edges is held on thescreen. However, as the web moves towards the front end F, suction isalso provided at the bottom of the U shape in order to form a centercore of material 124 about which the layer 122 may be wrapped by thescreen to form a cylindrical product.

EXAMPLE 11

Fiber materials are individualized by lickerins, doffed, and theindividualized fibers are entrained in air streams 104 promoted by asuction means in the suction box 105. In the embodiment shown, thetrough 102, perforated support 106 and the U-shaped portion of belt 101are disposed within a recess in the top of the suction box 105. The ductplates 108 form a mutual seal with the trough 102 and a suction box wall113.

In a first phase of operation, shown in FIG. 20 (section 20A-20A of FIG.19), a first mix of fibers e.g. those with good wicking properties areentrained in a first stream 104a toward the rear end R. These fibers aredeposited on the U-shaped portion of belt 101. The suction is controlledso as to influence the air streams in a predetermined manner, resultingin a desired deposition pattern of a generally uniform height on theU-shaped belt. In this manner, the fibers are distributed in a uniformU-shaped outer layer 122, over a rearward portion of the condensing zoneC corresponding to the fiber material introduced to a correspondingrearward portion of the lickerins.

In a second phase, the belt 101 moves forward, carrying layer 122. Asshown in FIG. 20B, a second mix of fibers, e.g. high absorbency fibers,is entrained in a second stream 104b and is deposited on top of layer122 as a core layer 124. Suction may again be advantageously controlledto influence the fiber deposition, but is less critical during thisphase. In fact the suction may be predominantly in the middle so as toform the fibrous structure shown in FIG. 20B. The rate of fiberdeposition is controlled, so that the resulting layer 124 achieves adesired depth. In the embodiment shown, the core layer 124 has a depththat is less than the depth of the trough 102, and the top of the layer124 is below the walls of outer layer 122.

Once the core fibers are deposited as layer 124 within a forward regionof condensing zone C (corresponding to section 20B--20B in FIG. 19), theU-shaped portion of belt 101 exits the condensing zone C at the frontend F.

In a third phase, shown in FIG. 20C (section 20C--20C of FIG. 19), thebelt 101, which now supports a condensed web having a curved crosssection, is introduced to forming shoes or guides 112 supported by ashoe support 114. In the embodiment shown, the shoes 112 are in the formof a convergent tube. The belt 101 and the web containing layers 120 and124 are further deformed by guides 112 into a circular shape. When thedepth of core layer 124 is less than the depth or circumferential lengthof layer 122, as shown, the guides 112 cause the ends of outer layer 122to meet, thereby uniformly enfolding the core layer 124 within acylindrical outer layer. If outer layer 122 contains a heat fusiblematerial, heat may be applied to the outer layer to stabilizecircumferentially the structure to keep the product in the cylindricalshape.

The resulting nonwoven cylindrical product is a uniform radially layeredweb having an inner core of absorbent material surrounded by a sheath ofmaterial with good wicking properties. The composite web has a circularcross-section, and may be adapted to a number of uses. For example, anadvantageous feminine hygiene tampon product can be obtained byproviding a core layer of highly absorbent fibers and an outer layer offibers having good wicking properties. In another embodiment, highlyabsorbent particles delivered to the air stream 104b can be substitutedfor some or all of the highly absorbent fibers.

It will be appreciated by skilled practitioners that many more radiallylayered products can be made according to this method and apparatus, andthat the specific embodiment described is illustrative rather thanlimiting.

Other Variations

Various other products can be made in segments by starting and stoppingthe condenser screen and by starting and stopping or sequentiallyfeeding the various fiber materials to the lickerins. Also, fibers maybe included which provide properties to the product other than moisturehandling. For example a fibrous material with great resiliency may beused to give a product, e.g. a napkin, a springy characteristic thatmakes it feel like a plush material.

As another example, the product shown in FIG. 7 can be formed with thepresent invention to have a top layer of 70% polyester and 30% syntheticpulp. The middle is a transition region and the bottom layer is 90% pulpand 10% synthetic pulp used as a binder. This is useful as an adultincontinence product in which the upper layer is in contact with theuser's skin. One object of this product is to keep the absorbent pulpaway from the user's skin.

A still further product may have an upper layer of 100% polyester, whichis nonabsorbent and resilient. The middle layer may be a mixed blend ofpolyester and pulp, while the bottom layer is pulp and synthetic pulp,which is resilient and absorbent.

While the present invention has been particularly shown and describedwith reference to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention. In particular, when multiple sources are fed to a lickerinthey need not each occupy 50% of the space. One may occupy more spacethan another and there may be gaps between them. Also other products maybe created by sequentially feeding the products or halting the feedingfor certain periods.

What is claimed is:
 1. A method of forming a web of fibers comprisingthe steps of: feeding at least one source of fibrous material intoengagement with one of two lickerins and feeding at least one othersource of fibrous material of different composition into engagement withthe other lickerin, said lickerins rotating toward each other aboutparallel axes such that the fibrous material is opened to formindividualized fibers; doffing the fibers form the lickerins in the formof fiber streams;directing the fiber streams toward each other and intoa mixing zone; selectively intercepting and redirecting at least part ofeach fiber stream within the mixing zone with at least two independentlyvertically movable baffle segments, each said baffle segmentcorresponding to a longitudinal segment along the operating length ofsaid lickerins, at least one of said baffle segments being at adifferent vertical height; receiving and accumulating the fiber streamson a conveying belt, after they have passed through the mixing zone, toform a web of material; and moving the conveying belt parallel to theaxes of the lickerins.
 2. A method of forming a web as claimed in claim1, wherein two sources of fiber materials are fed to at least one ofsaid lickerin by independent feeding means segments, each feeding meanssegment corresponding to one of said longitudinal segments of saidlickerins.
 3. A method of forming a web of fibers comprising the stepsof:feeding at least two sources of different fibrous material atindependent separate speeds into independent engagement with one of twolickerins rotating toward each other about parallel axes and at leastone source of fibrous material to the other lickerin, such that thefibrous material is opened to form individualized fibers, said feedingbeing performed by feed segments corresponding to longitudinal segmentsalong the operating length of said at least one lickerin; doffing thefibers from said lickerins in the form of fiber streams; directing thefiber streams into a mixing zone; selectively intercepting andredirecting at least part of each said fiber stream within said mixingzone with at least two independently vertically movable verticalbaffles, at least one of said baffle segments being at a differentvertical height; receiving the fiber streams on a conveying belt, afterthey have passed through the mixing zone, in condensing zone locatedbeyond the mixing zone; moving the conveying belt parallel to the axesof the lickerins; and accumulating the fibers from the fiber streams onthe conveying belt to form a web of material.
 4. A method as claimed inclaims 1 or 3, further comprising the step of spraying a powder onto theforming web by introducing the powder into said fiber stream.
 5. Amethod of forming a cylindrical web of fibers comprising the stepsof:feeding a first source of fibrous material into engagement with afirst lickerin; feeding a second source of fibrous material intoengagement with a second lickerin arranged with its axis parallel to theaxis of said first lickerin; rotating said first and second lickerinstoward each other about their axes such that the fibrous material isopened so as to form individualized fibers; doffing the fibers from thefirst and second lickerins in the form of two fiber streams directedtoward each other and a mixing zone; forming a foraminous flat conveyingbelt into a U-shape as it enters a condensing zone beyond the mixingzone in the direction of travel of the fiber streams; intercepting thestreams of fibers, after they have passed through the mixing zone, withthe U-shaped conveying belt; moving the conveying belt parallel to theaxes of the lickerins; accumulating the fibers from the fiber streams onthe conveying belt to form a web of material; guiding the U-shapedconveying belt into a cylindrical shape to form the cylindrical web;fixing said cylindrical web in the cylindrical shape; releasing theconveying belt back to a flat shape from said cylindrical shape; andseparating the resulting cylindrical web product from the conveyingbelt.
 6. A method as claimed in claim 5, wherein said accumulating stepcomprises the steps of:selectively directing said fibers topredetermined zones on the inner surface of said U-shaped conveying beltby entraining said fibers in at least one air stream; forming said airstream by a vacuum force created beyond the conveying belt; and varyingthe vacuum force from a minimum at the center of said conveying belt toa maximum at the edges of said belt during at least a portion of timethe conveying belt is in the condensing zone.
 7. A method as claimed inclaim 6 further including the step of inserting at least one baffle intothe mixing zone so as to at least partially block the fiber streams andvary the composition of the web.
 8. A method of forming a fibrousstructure as claimed in claim 5, wherein the step of feeding a firstsource of fibrous materials involves simultaneously feeding at least twodifferent fibrous material with generally the same functional fiberlength to different portions of the first lickerin.
 9. A method offorming a fibrous structure according to claim 5, additionallycomprising the step of depositing a powdered material onto the formingweb.